[Cellular and fibrillar organization of the locomotor regions of the brain stem in cats].

Cellular and fibrillar organization of the hypothalamic (HLR) and mesencephalic (MLR) locomotor regions of the brain stem has been studied in cats by means of staining the nervous tissue after Nissl and Sokolyansky. Morphometric investigations of neurons in these regions has been performed in frontal and sagittal slices. Within the limits of the HLR ad MLR there are about 45,000 of neurons, which are organized as various nuclei, the MLR cells arranging in them more compactly in comparison to diffusely ++ scattering HLR neurons.

[Descending neuronal projections to the lumbar segment of the spinal cord of cats].

In the experiments, performed on cats by means of retrograde axonal horseradish peroxidase transport, localization of the sources of descending supra- and propriospinal projections to the area of the lumbar parts of the spinal cord, where the generator of locomotor movements is located. After local administration of horseradish peroxidase into the spinal cord, the greatest amount of the labelled neurons is observed in the ipsilateral reticular formation and in the Koelliker-Fuse nucleus. Comparison of the number of neurons, forming the descending projections from the I cervical up to the IV lumbar segments demonstrates an essential predominance of short propriospinal connections over the long, as well as over the supraspinal ones.

[Afferent projections of the bulbar locomotor region located in the medial reticular formation of the brain stem].

Afferent projections to the functionally identified bulbar locomotor region which is situated in the medial reticular formation were studied in cats and rats by means of horse-radish peroxidase technique. Cells of origin of such projections were found not only in hypothalamic and mesencephalic locomotor regions but also in the interstitial nucleus of Cajal and adjacent structures and in the ventral part of the caudate nucleus.